Leonardo Da Vinci had a vision. His insight was for improved vision for people with less than perfect sight. He delved into the science of light and sight and devised a solution to eye defects. What was that science? How did Da Vinci come up with those conclusions? How did he envision the contact lens? We'll answer those questions here with a look at how contact lenses work.
Perfect vision occurs when light rays converge at a point directly on the retina (the back of the eyeball). If light rays fail to hit that point at exactly the same point, then vision becomes blurry. So the purpose of corrective lenses is to refocus light rays so they do converge at that point on the retina.
There are a number of common eye, or vision defects. Two of the most common are myopia, or short-sightedness, and hyperopia, or long-sightedness. People with myopia can see clearly up close but not at a distance. Those with hyperopia see better at a distance than close up and sometimes experience difficulty bringing their vision into sharp, clear focus.
A couple of other well-known irregular eye conditions are astigmatism and presbyopia. A person with astigmatism has an irregularly-shaped cornea, which causes light images to focus on two separate points in the eye. Presbyopia is commonly known as an "ageing eye". In this condition the eye loses its ability to shift focus between far and near objects. An example of difficulty caused by this condition is shifting focus between the road and the speedometer while driving.
So these are the problems that could arise with someone's sight. However, with advancing contact lens technology, most common vision conditions can be treated with contact lenses, and in the last few years, many more options have been made available for treating each kind of problem.
Contact lenses are small, thin transparent discs, designed to sit on your cornea and correct your vision. You'd think that something that just rests on top of your eye would fall out, but not so. The moisture in your eyes acts as an adhesive, keeping the lenses in place.
The actual shape of your contact lenses is determined by the actual shape of your eye. Of course, they have to be uniform, if the lens is to stay in place. So the inner surface of the lens is fit to the shape of your eye.
The purpose of contact lenses is the same as eyeglasses - to correct vision defects. Many people find wearing eyeglasses a problem. Removing them and putting them on constantly throughout the day, as well as having them slide down their nose or fogging up in the wintertime, can be most frustrating. But with the creation of the contact lens, people could have the vision correction they needed without the hassle of eyeglasses.
In the beginning, the first modern-day contact lenses were made of hard plastic, which was hard on the eyes and required a lot of maintenance to prevent irritation of the eye. A saline solution was applied frequently to keep the eyes moist.
Then came the development of soft flexible contact lenses. The range of possibilities expanded.
Soft contact lenses are made from a gel-like plastic that contains from a good percentage of water. Being softer, they're more comfortable. And they last longer, too, some for up to a year with proper care.
Contact lens use is widespread these days. The industry is creating more and more different types and uses of contact lenses. Check with your ophthalmologist or optometrist to see which contact lens is best for your lifestyle!
Contact lenses! Would you believe, way back in 1508, Leonardo Da Vinci sketched and described several forms of contact lenses?
Although the idea of contact lenses had been developed, the technology had not. Step by step, the process was built through the years, from spectacles to today's contact lenses. Let's look at each of those steps.
1632 - A French philosopher, Ren Descartes, added to his deep reasonings, the idea of a corneal contact lens. 1704 - A French surgeon, Jean Mry, presented a paper to the French Royal Academy of Sciences, reporting that, by submerging the head of a living cat in water, the irregularities of the surface of the cornea were flattened by the water. We're not sure how he came up with this idea - and we may not want to know! However, the discovery here was that the living eye could be neutralized, or corrected, and that is an essential part of optical contact systems. 1801 - Thomas Young, with his medical education, did experiments with light and glass. His conclusion resulted in the development of Descartes idea - a -inch long, water-filled glass tube, which contained a microscopic lens at the outer end. He used this to correct his own vision. 1827 - An English astronomer, Sir John Herschel, introduced the idea of grinding a contact lens to conform exactly to the eye's surface. 1887 - A German glassblower, F.E. Muller, manifested Sir John Herschel's idea into an actual glass lens that covered the entire eye. 1888 - A. Eugen Fick, a Swiss physician, and Edouard Kalt, a French optician, simultaneously, but independently, used contact lenses to correct optical defects.
A number of years went by until the technology was developed to create the contact lenses as we know them today. But finally, in 1929, a physician, perfected a method of making molds of living eyes and using them to form lenses that fit exactly to the shape of the eye.
Then the United States got into the act - the first hard plastic contact lenses made in America and they were quite bothersome and could only be tolerated for about 4 hours at which point they had to be removed to replace the saline solution that filled the space between the eye and the lens.
As time progressed, so did the science of contact lenses. 1950 marked the beginning of the modern-day contact lens. A buffer solution was no longer needed, so the lenses could be worn all day.
Up to this point, contact lenses had been made of hard plastic. Then, in 1960, a change came - the soft, water-absorbing plastic contact lens and it was so inexpensive that he envisioned they could be worn on a disposable basis.
Nearly every year, there was a new development since 1971 and here's how fast technology was developing new creations:
1978 - toric contact lens ( for astigmatism) 1979 - rigid gas permeable (RGP) contact lens 1980 - tinted daily-wear soft contact lens 1981 - extended-wear soft contact lens 1982 - bifocal daily-wear soft contact lens 1983 - tinted RGP contact lens 1986 - extended-wear RGP contact lens 1987 - disposable soft contact lens 1987 - soft contact lens that changes eye color 1987 - multipurpose lens care products 1991 - planned replacement contact lens 1991 - daily-wear 2-week replacement contact lens 1992 - disposable tinted contact lens 1995 - daily disposable contact lens 1995 - RGP contact lens with low silicone content 1996 - disposable contact lens with ultra-violet absorber
There are a number of different types of soft contact lenses. Here are some of the most common:
Disposable lenses - replaced every day, every few weeks or every few months Daily-wear lenses - removed nightly Oxygen permeables (RPGs) - transmit oxygen; they don't contain water, so they resist deposits and bacteria Color-tinted lenses - change the natural eye color Disposable contact lenses with ultra-violet absorber - protects against the sun's harmful ultra-violet rays. These are the most common types of contact lenses. There are also some specialty contact lenses used for special effects in movies. As time goes on, there'll be many more...Do the research! - 16651
Perfect vision occurs when light rays converge at a point directly on the retina (the back of the eyeball). If light rays fail to hit that point at exactly the same point, then vision becomes blurry. So the purpose of corrective lenses is to refocus light rays so they do converge at that point on the retina.
There are a number of common eye, or vision defects. Two of the most common are myopia, or short-sightedness, and hyperopia, or long-sightedness. People with myopia can see clearly up close but not at a distance. Those with hyperopia see better at a distance than close up and sometimes experience difficulty bringing their vision into sharp, clear focus.
A couple of other well-known irregular eye conditions are astigmatism and presbyopia. A person with astigmatism has an irregularly-shaped cornea, which causes light images to focus on two separate points in the eye. Presbyopia is commonly known as an "ageing eye". In this condition the eye loses its ability to shift focus between far and near objects. An example of difficulty caused by this condition is shifting focus between the road and the speedometer while driving.
So these are the problems that could arise with someone's sight. However, with advancing contact lens technology, most common vision conditions can be treated with contact lenses, and in the last few years, many more options have been made available for treating each kind of problem.
Contact lenses are small, thin transparent discs, designed to sit on your cornea and correct your vision. You'd think that something that just rests on top of your eye would fall out, but not so. The moisture in your eyes acts as an adhesive, keeping the lenses in place.
The actual shape of your contact lenses is determined by the actual shape of your eye. Of course, they have to be uniform, if the lens is to stay in place. So the inner surface of the lens is fit to the shape of your eye.
The purpose of contact lenses is the same as eyeglasses - to correct vision defects. Many people find wearing eyeglasses a problem. Removing them and putting them on constantly throughout the day, as well as having them slide down their nose or fogging up in the wintertime, can be most frustrating. But with the creation of the contact lens, people could have the vision correction they needed without the hassle of eyeglasses.
In the beginning, the first modern-day contact lenses were made of hard plastic, which was hard on the eyes and required a lot of maintenance to prevent irritation of the eye. A saline solution was applied frequently to keep the eyes moist.
Then came the development of soft flexible contact lenses. The range of possibilities expanded.
Soft contact lenses are made from a gel-like plastic that contains from a good percentage of water. Being softer, they're more comfortable. And they last longer, too, some for up to a year with proper care.
Contact lens use is widespread these days. The industry is creating more and more different types and uses of contact lenses. Check with your ophthalmologist or optometrist to see which contact lens is best for your lifestyle!
Contact lenses! Would you believe, way back in 1508, Leonardo Da Vinci sketched and described several forms of contact lenses?
Although the idea of contact lenses had been developed, the technology had not. Step by step, the process was built through the years, from spectacles to today's contact lenses. Let's look at each of those steps.
1632 - A French philosopher, Ren Descartes, added to his deep reasonings, the idea of a corneal contact lens. 1704 - A French surgeon, Jean Mry, presented a paper to the French Royal Academy of Sciences, reporting that, by submerging the head of a living cat in water, the irregularities of the surface of the cornea were flattened by the water. We're not sure how he came up with this idea - and we may not want to know! However, the discovery here was that the living eye could be neutralized, or corrected, and that is an essential part of optical contact systems. 1801 - Thomas Young, with his medical education, did experiments with light and glass. His conclusion resulted in the development of Descartes idea - a -inch long, water-filled glass tube, which contained a microscopic lens at the outer end. He used this to correct his own vision. 1827 - An English astronomer, Sir John Herschel, introduced the idea of grinding a contact lens to conform exactly to the eye's surface. 1887 - A German glassblower, F.E. Muller, manifested Sir John Herschel's idea into an actual glass lens that covered the entire eye. 1888 - A. Eugen Fick, a Swiss physician, and Edouard Kalt, a French optician, simultaneously, but independently, used contact lenses to correct optical defects.
A number of years went by until the technology was developed to create the contact lenses as we know them today. But finally, in 1929, a physician, perfected a method of making molds of living eyes and using them to form lenses that fit exactly to the shape of the eye.
Then the United States got into the act - the first hard plastic contact lenses made in America and they were quite bothersome and could only be tolerated for about 4 hours at which point they had to be removed to replace the saline solution that filled the space between the eye and the lens.
As time progressed, so did the science of contact lenses. 1950 marked the beginning of the modern-day contact lens. A buffer solution was no longer needed, so the lenses could be worn all day.
Up to this point, contact lenses had been made of hard plastic. Then, in 1960, a change came - the soft, water-absorbing plastic contact lens and it was so inexpensive that he envisioned they could be worn on a disposable basis.
Nearly every year, there was a new development since 1971 and here's how fast technology was developing new creations:
1978 - toric contact lens ( for astigmatism) 1979 - rigid gas permeable (RGP) contact lens 1980 - tinted daily-wear soft contact lens 1981 - extended-wear soft contact lens 1982 - bifocal daily-wear soft contact lens 1983 - tinted RGP contact lens 1986 - extended-wear RGP contact lens 1987 - disposable soft contact lens 1987 - soft contact lens that changes eye color 1987 - multipurpose lens care products 1991 - planned replacement contact lens 1991 - daily-wear 2-week replacement contact lens 1992 - disposable tinted contact lens 1995 - daily disposable contact lens 1995 - RGP contact lens with low silicone content 1996 - disposable contact lens with ultra-violet absorber
There are a number of different types of soft contact lenses. Here are some of the most common:
Disposable lenses - replaced every day, every few weeks or every few months Daily-wear lenses - removed nightly Oxygen permeables (RPGs) - transmit oxygen; they don't contain water, so they resist deposits and bacteria Color-tinted lenses - change the natural eye color Disposable contact lenses with ultra-violet absorber - protects against the sun's harmful ultra-violet rays. These are the most common types of contact lenses. There are also some specialty contact lenses used for special effects in movies. As time goes on, there'll be many more...Do the research! - 16651
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